Integrated electro-optic package for reflective spatial light modulators

ABSTRACT

An array of reflective LCSLM pixels and control circuits formed on a substrate with a light polarizing layer positioned in overlying relationship to the array. A housing having the array and polarizing layer mounted therein, and defining an opening covered by an optical layer with a reflective member affixed to the optical layer. A light source mounted in the housing so that light is directed onto the reflective member and is reflected uniformly onto the polarizing layer. Electrical connections are made from the array, through leads in the housing and to external contacts. The optical layer including a diffuser forming an image plane for reflected light from the array.

FIELD OF THE INVENTION

The present invention pertains to reflective spatial light modulatorsand more specifically to packaging and illumination of reflectivespatial light modulator devices.

BACKGROUND OF THE INVENTION

Liquid crystal spatial light modulators (LCSLMs) are very popular at thepresent time and are utilized in a great variety of direct view typedisplays, such as digital watches, telephones, lap-top computers and thelike. In general, liquid crystal devices are illuminated with arelatively large, separately mounted light source, preferably from therear (back-lighting), so that most of the light travels directly throughthe liquid crystal and outwardly to the eye of a viewer. Direct viewdisplays require a substantial amount of light for suitable viewing,generally about 25 fL to be visible in office environments and more than100 fL to be visible in an outdoor environment. To provide this amountof light or luminance at the outlets of the LCSLMs requires a relativelybright, and large, light source.

Further, LCSLMs used in display applications require polarized light anda diffuser placed in the optical path. Light entering the LCSLMs must bepolarized, and an analyzing polarizer must be placed in the path ofexiting light to differentiate between which LCSLM pixels are ON andwhich are OFF. A diffuse element, either near the modulating LCSLM or asa screen in a projection system, must be used. Generally, the result isto produce a relatively large and cumbersome package, usually withseveral discrete components.

This problem severely limits the usefulness of liquid crystal displays.For example, in portable electronic devices such as telephones, two-wayradios, pagers, etc. the displays are limited to a few alpha-numericdigits. Generally, if a small portable device is desired, the displaymust be reduced to a very small number of digits, since the size of thedisplay dictates the minimum size of the device into which it isintegrated.

One way to alleviate package size problems is to use a very small liquidcrystal spatial light modulator (LCSLM) as the image source, with amagnifying optical system. This can take the form of a projectiondisplay, in which light modulated by the liquid crystal is projected bythe optical system onto a diffusing screen, or it can take the form of avirtual display, where the optical system creates a large virtual imageof the small real image created by the LCSLM.

By using the LCSLM in a reflective mode, a reflective LCSLM is formed,which can be built onto a silicon substrate that contains the drivecircuitry and other related electronics. When using this configurationas a virtual image display, the number of discrete components stillresults in a large and cumbersome package. At present, it is extremelydifficult to provide a sufficiently large light source, and to mount thelight source and the polarizers so that the reflective LCSLM is properlyilluminated and can be viewed conveniently.

Thus, it would be beneficial to have reflective LCSLMs with improvedpackaging and lighting so they would be more versatile.

It is a purpose of the present invention to provide new and improvedintegrated electro-optic packaging for reflective spatial lightmodulators.

It is another purpose of the present invention to provide new andimproved integrated electro-optic packaging for reflective spatial lightmodulators utilizing improved light sources.

It is still another purpose of the present invention to provide new andimproved integrated electro-optic packaging for reflective spatial lightmodulators which are useful in forming a virtual image.

It is a further purpose of the present invention to provide new andimproved integrated electro-optic packaging for reflective spatial lightmodulators which is small and compact enough to be utilized in portableelectronic equipment.

It is a still further purpose of the present invention to provide newand improved integrated electro-optic packaging for reflective spatiallight modulators which requires a sufficiently small amount of power tobe utilized in portable electronic equipment.

It is yet another purpose of the present invention to provide new andimproved integrated electro-optic packaging for reflective spatial lightmodulators which includes molded components that are easily andinexpensively fabricated and assembled.

SUMMARY OF THE INVENTION

The above described problems and others are at least partially solvedand the above purposes and others are realized in an integratedelectro-optic package for reflective spatial light modulators includingan array of reflective spatial light modulator pixels formed on asubstrate with each pixel including a control circuit formed in thesubstrate, each control circuit including control terminals adjacent anouter edge of the substrate, a mirror positioned on the substrate inoverlying relationship to the control circuit, and a spatial lightmodulator material positioned in overlying relationship to the mirror sothat light passing through the spatial light modulator material isreflected back through the spatial light modulator material. A lightpolarizing layer is positioned in overlying relationship to the array ofreflective spatial light modulator pixels.

A housing with an internal cavity is formed to receive the array ofreflective spatial light modulator pixels and the light polarizing layertherein. The housing defines therein an opening generally parallel withand spaced from the light polarizing layer and including an opticallayer positioned in the opening with an at least partially reflectivemember affixed to the optical layer.

A light source is mounted in the housing so that light emanating fromthe light source is directed onto the reflective member and is reflectedsubstantially uniformly onto the light polarizing layer. The opticallayer includes a diffuser which forms an image plane for reflected lightfrom the array of reflective spatial light modulator pixels. The housingalso provides electrical connections to the array.

The above described problems and others are at least partially solvedand the above purposes and others are further realized in a method offabricating an integrated electro-optic package for reflective spatiallight modulators including providing the housing by some convenientmethod, such as molding or the like. The housing includes a lightsource, a polarizing layer and a diffuser to provide an image, as wellas electrical leads positioned to connect to the reflective spatiallight modulators and provide an external electrical connection thereto.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the drawings:

FIG. 1 is a simplified and enlarged sectional view of a reflectiveliquid crystal spatial light modulator stack;

FIG. 2 is a semi-schematic perspective view for illustrating theoperation of the reflective liquid crystal spatial light modulatorstack;

FIG. 3 is a perspective, semi-schematic, view of an integratedelectro-optic package, including a reflective liquid crystal spatiallight modulator stack, embodying the present invention;

FIG. 4 is an enlarged sectional view of the integrated electro-opticpackage illustrated semi-schematically in FIG. 3;

FIG. 5 is a perspective view of dual image manifestation apparatus;

FIG. 6 is a perspective view of the dual image manifestation apparatusillustrated in FIG. 5;

FIGS. 7, 8 and 9 illustrate a front view, side elevational view, and topplan, respectively, of image manifestation apparatus utilizing theintegrated electro-optic package illustrated in FIG. 3; and

FIG. 10 is a 4× magnified view in side elevation of the apparatus ofFIG. 9.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring specifically to FIG. 1, a simplified and enlarged sectionalview of a reflective liquid crystal spatial light modulator (LCSLM)stack 10 is illustrated. Stack 10 includes a substrate 11 formed of anyconvenient semiconductor material, such as silicon, silicon carbide,gallium arsenide, etc. in which integrated electronic circuits can beformed. As will be explained in more detail presently, the integratedelectronic circuits include one driver circuit and associated addressingand switching circuitry for each LCSLM formed in stack 10. A pluralityof bond or terminal pads 12 are formed adjacent the edges of substrate11 and are in electrical communication with the integrated electroniccircuits so that individual addressing of the electronic circuits ispossible.

A two dimensional array of reflective metal pads 15 are formed on theupper surface of substrate 11, which metal pads 15 each define areflective LCSLM pixel. In the present embodiment, metal pads 15 aremade of aluminum or any metal that can be conveniently patterned on thesurface of substrate 11 and which will reflect light impinging thereon.Each metal pad of the plurality of metal pads 15 is electricallyconnected to a driver circuit and addressing and switching circuitry soas to form one contact for energizing the liquid crystal material in thespace above metal pad 15, forming a pixel.

In this embodiment, metal pads are formed in rows and columns and theaddressing and switching circuitry (not shown) includes row and columnelectrical buses and electronic switches coupled to metal pads 15 sothat each metal pad 15 can be individually addressed. The row and columnelectrical buses are electrically connected to the plurality of bond orterminal pads 12 formed adjacent the edges of substrate 11 for externalcommunication (addressing and controlling) with individual metal pads15. Further, it should be noted that metal pads 15 along with anydriving, addressing and switching circuitry is formed in substrate 11and coupled to the plurality of bond or terminal pads 12 with pixelsdefined and formed thereabove.

A generally tubular glass spacer 20 is fixedly attached to the uppersurface of substrate 11 by any convenient means, such as adhesive,chemical bonding, growing and etching layers, etc. It will of course beunderstood that spacer 20 could be formed in a variety of otherembodiments and the present structure is illustrated only for purposesof this explanation. Spacer 20 has an inner opening 21 definedtherethrough with sufficient size to encircle the two dimensional arrayof reflective metal pads 15. The cavity formed by opening 21 in spacer20 in conjunction with the upper surface of substrate 11 is filled withliquid crystal material 22. Typical examples of liquid crystal materialwhich can be used for this purpose are disclosed in U.S. Pat. No.4,695,650, entitled "Liquid Crystal Compounds and CompositionsContaining Same", issued Sep. 22, 1987 and U.S. Pat. No. 4,835,295,entitled "Ferroelectric Liquid Crystal Compounds and Compositions",issued May 30, 1989.

A glass window 25 has a layer 24 of transparent electrically conductivematerial, such as indium-tin-oxide (ITO) or the like, formed thereon todefine a second contact, which, in conjunction with metal pads 15 andliquid crystal material 22 form a complete two dimensional array ofLCSLMs. Glass window 25 is fixedly attached to the upper surface ofglass spacer 20 so that electrically conductive material layer 24 on thelower surface thereof is in contact with liquid material 22 and liquidmaterial 22 is contained within the cavity defined by the upper surfaceof substrate 11, inner opening of spacer 20 and glass window 25. It willbe apparent to those skilled in the art that electrically conductivematerial layer 24 can be formed in a separate or discrete layer that issimply positioned on glass spacer 20 and partially sandwichedtherebetween during assembly.

Electrically conductive material layer 24 is a common second electricalconnection for each pixel defined by metal pads 15 and is connected by aconductive lead to a bond pad 26 adjacent the outer edges of glassspacer 20. Bond pad 26 is then electrically connected to a bond pad 27on substrate 11 by any convenient means, such as wire bond 28, a feedthrough connector in the edges of glass spacer 20 (not shown), etc. Bondpad 27 is adapted to have applied thereto a common potential, such asground or some fixed voltage, which in cooperation with variouspotentials applied to metal pads 15 turn ON, turn OFF, and reset (ifnecessary) each LCSLM pixel.

It will be understood that various liquid crystal and ferroelectricliquid crystal material can be provided which will operate in differentmodes in response to different signals or potentials applied thereto.Reflective LCSLMs can be provided, for example, that: rotate thepolarization of light impinging thereon when a predetermined potentialis applied thereacross and do not rotate the polarization when thepotential is removed; rotate the polarization of light impinging thereonwhen no potential is applied thereacross and do not rotate thepolarization when a predetermined potential is applied; rotate thepolarization of light impinging thereon when a first predeterminedpotential is applied thereacross and do not rotate the polarization whena second (lower or higher) potential is applied; etc. Further, commonnematic liquid crystal spatial light modulators do not have a memory anddo not have to be reset after each application of a potential, butferroelectric liquid crystal material has a memory and, at least in someapplications, ferroelectric liquid crystal spatial light modulators mayrequire a reset (or other modifying) signal between normal switchingsignals. Generally, the term "activate" or "activating" will be used toindicate that a signal or signals are being applied to or removed from apixel to cause the pixel to change, regardless of the mode of operation,so as to produce a desired result, which desired result will beapparent.

Glass window 25 completes reflective LCSLM stack 10 which includes a twodimensional array of reflective liquid crystal pixel elements, each ofwhich are individually addressable through bond pads 12. To turn a pixelON a potential must be applied between the upper and lower contacts forthat specific pixel. With no potential applied, the pixel is normally inan OFF condition. Glass plate 25 defines a light input and light outputfor each of the pixels in the two dimensional array of reflectiveLCSLMs. While the present embodiment is explained using liquid crystalmaterial in the pixels, it should be understood that other types ofspatial light modulators might be utilized in the pixels, including, forexample, other types of light modulating liquid or solid material,mirrors or other reflective material, etc.

Referring now to FIG. 2, the operation of reflective LCSLM stack 10 isbriefly explained. A light source 30 is provided, which may be any lightemitting device capable of providing sufficient light for the operationexplained. Light from source 30 is diffused in a plate 31 and polarizedin a second plate 32 before illuminating stack 10. Diffusing plate 31 isprovided to spread the light from source 30 over stack 10. Polarizingplate 32 polarizes the light into a vertical polarization, for example,prior to the light impinging on stack 10.

The liquid crystal, for example ferroelectric liquid crystal material,in stack 10 rotates the polarization of light passing therethrough whenin the energized or ON condition (this operating mode is used only forpurposes of this explanation), just as in a standard twisted nematicliquid crystal display. Thus, light passing through glass plate 25 andliquid crystal material 22 and reflected from pads 15 back throughliquid crystal material 22 and glass plate 25 gets a 90° polarizationrotation in each pixel that is energized. For all pixels in the arraythat are not energized the light passing therethrough is not changed inpolarization.

An analyzing polarization plate 35 is positioned so that light reflectedthrough the plurality of pixels in the array of stack 10 passestherethrough. If, for example, plate 35 is polarized horizontally alllight reflected from pixels that are energized, which light is rotated90° in polarization, will pass through plate 35, while light reflectedfrom pixels which are not energized and which is not rotated inpolarization will be blocked. If plate 35 is vertically polarized, thesame as plate 32, light from pixels which are not energized will passtherethrough and light from pixels which are energized will be blocked.It will be understood that pixels which are constructed to operate inany other mode, such as those described above, may require differentorientation of plates 32 and 35.

Referring now to FIGS. 3 and 4, which illustrate an enlarged perspectiveview of an integrated electro-optic package 40 embodying the presentinvention and a greatly enlarged sectional view, respectively. Package40 includes a housing 41 having a cavity 42 formed therein fabricated byany convenient means, such as molding, etching, or the like. As anexample of a preferred embodiment, housing 41 is molded using anyconvenient plastic, such as the inexpensive black encapsulating plasticnormally used for encapsulating integrated circuits and the like. In thepreferred embodiment, support 41 is formed of plastic with a relativelylow coefficient of expansion (e.g. 20 ppm or less) so that housing 41,substrate 11, glass spacer 20 and glass window 25 all have a temperaturecoefficient of expansion within a range that allows reasonabletemperature cycling of the structure without causing critical ordamaging stresses.

Cavity 42 extends completely through housing 41 and is formed so thatstack 10 (see FIG. 1) can be nestingly positioned therein from the lowerend with glass window 25 directed toward the opposite end of cavity 42.A polarizing plate 45 is positioned in cavity 42 generally in overlyingrelationship to glass plate 25 so that all light entering or exitingglass plate 25 passes through and is polarized by polarizing plate 45.It will of course be understood that polarizing plate 45 can be aseparate, discrete plate positioned in cavity 42 before inserting stack10, or polarizing plate 45 can be deposited on the surface of glassplate 25, either as a portion thereof or in addition thereto.

Housing 41 further includes an optical layer 50 positioned over cavity42 so as to close the opening in the upper surface thereof. Opticallayer 50 is, for example, a layer of clear plastic, glass, etc. Also aplurality of at least partially reflective members 52 are affixed to theinner surface (or lower surface, in FIG. 4) of optical layer 50 so as tobe directed inwardly toward polarizing layer 45. A plurality of lightsources 54 are mounted in alcoves 55 in housing 41 to the side of, butin communication with, cavity 42. Alcoves 55 are formed so that lightemanating from light sources 54 is directed onto reflective members 52.Further, reflective members 52 are formed and positioned so that lightfrom light sources 54 is reflected substantially uniformly onto lightpolarizing layer 45.

While a plurality of light sources 54 in alcoves 55 and reflectivemembers 52 are illustrated in the present embodiment for purposes ofexplanation, in some applications only one of either light sources 54and/or reflective members 52 may be required to provide thesubstantially uniform illumination. Further, in the preferred embodimentlight sources 54 include light emitting diodes (LED) and each lightsource 54 can include a single LED or several LEDs. For example,currently known GaN LEDs are capable of producing output power ofapproximately 40 mA and 2 mW, which translates into an output power ofapproximately 11 lumens/watt so that a substantial amount of light isproduced by each GaN LED.

In another example, three LEDs (a red, a green and a blue LED) areprovided in each alcove 55 (one or more) and are alternately activatedto form three different color light sources 54, each of which fully anduniformly illuminates stack 10 at different times. By activating eachLCSLM (pixel) in stack 10 in accordance with the amount of each color(red, green, or blue) required in each pixel during the time that thatcolor LED is activated, a complete and full color image is produced foreach cycle of the three LEDs.

In a preferred embodiment, reflective members 52 are one or morediffractive optical elements (DOE) positioned on or formed in thesurface of optical layer 50. Depending upon the angle at which lightfrom light sources 54 strikes reflective members 52 and the relativeposition of polarizing layer 45 and stack 10, some redirection (otherthan a direct reflection) of light may be required of reflective members52 to substantially uniformly illuminate polarizing layer 45 and stack10. Diffractive optical elements can be relatively easily formed toperform this task while allowing substantially all reflected light fromstack 10, which passes through polarizing layer 45, to pass throughreflective members 52 and optical layer 50. It will of course beunderstood that reflective members 52 may incorporate other reflectivematerial, such as partially silvered mirrors and the like, instead of orin addition to the DOE.

Optical layer 50 also includes a diffuser 57 which forms an image planefor reflected light from the array of reflective spatial light modulatorpixels in stack 10. Diffuser 57 can be incorporated into optical layer50 as an additional layer, as illustrated in FIG. 4, it can beintegrated into optical layer 50 as an integral part thereof, or in someapplications optical layer 50 can be diffuser 57. Also, some additionaloptical elements (not shown) may be positioned in cavity 42 between theinner surface of optical layer 50 and polarizing plate 45, especially ifthe distance between diffuser 60 and polarizing plate 45 is great enoughto allow too much spreading of the reflected light. Such additionaloptical elements can provide additional magnification and/or partialcollimation prior to the light impinging upon diffuser 57.

Generally, diffuser 57 may be formed as an optical lens which isremoveably and/or adjustably mounted in the end opening of cavity 42. Ina specific example, diffuser 57 is formed in the shape of a disk withexternal threads on the outer periphery thereof, which threads arethreadidly engaged in internal threads on the inner surface of cavity42. Thus, diffuser 57 can be easily and quickly moved axially relativeto stack 10 to provide focusing of the image formed on diffuser 57. Itshould be understood that the diffusion required to produce a real imagefrom the light reflected by the array of LCSLMs can be provided by adiffusion element (not shown) positioned between polarizing plate 45 andlight sources 54, or, in some applications, by a diffusion materialpositioned on the surfaces of metal plates 15, or some combination ofthe above.

Cavity 42 may be further formed to receive, after receiving diffuser 57,single or multiple optical elements therein, such as refractive ordiffractive lenses, diffusers, filters, etc. The additional opticalelements can be formed separately from diffuser 57 or as a single unitwith diffuser 57. Also, it will be understood that diffuser 57 and/orextra optical elements can be mounted in lower cavity 52 by threadedengagement (as explained above) or by any other convenient means, suchas "snap-in" or frictional engagement.

In this specific embodiment, housing 41 includes a plurality ofelectrical leads 60 having a first end positioned in cavity 42 so as toelectrically engage bond pads 12 and 27 of substrate 11 with stack 10nestingly engaged in cavity 42. Opposite ends of electrical leads 60extend outwardly from the external surface of housing 41 and form pinsor external electrical terminals for the driver circuits and theswitching and address circuitry formed in substrate 11 for each LCSLMpixel. Electrical leads 60 are also positioned to provide an externalconnection for light sources 54. During the molding of housing 41,patterned electrical leads, imbedded electrical leads, or electricalleadframes are molded directly in housing 41.

Referring again to FIG. 3, a perspective view of integratedelectro-optic package 40, mounted on a driver board 80, is illustrated,while FIG. 4 illustrates integrated electro-optic package 40 and driverboard 80 in a cross-sectional view. Driver and switching circuits anddata processing circuits are fabricated in a plurality of integratedcircuits 82 and mounted on the upper surface of driver board 80 by anyconvenient method, such as bump bonding, wire bonding, direct mounting,etc. Electrical traces or wires are formed in driver board 80 and extendfrom the various pins or terminals of integrated circuits 82 intoelectrical contact with pins 60 of integrated electro-optic package 40.Driver board 80 can be constructed of any convenient material, such asprinted circuit board, FR4, glass, ceramic, etc. Again, integratedelectro-optic package 40 can be mounted on driver board 80 by anyconvenient method, such as simply plugging pins 60 into a matchingreceptacle, bump bonding, etc.

Thus, a new and improved integrated electro-optic package for reflectiveSLMs is disclosed which is relatively easy and inexpensive tomanufacture. The package ruggedly mounts the various optical componentswhile conveniently integrating electrical connections to the componentsand providing external connections thereto. Further, light sources,polarizers and a diffuser are conveniently integrated into a smallcompact package which is easily integrated into portable electronicequipment. By using LEDs for the light source, the size of the packageis further reduced and the electrical power required is also minimized.Also, by using multicolored LEDs images with partial or full color canbe formed.

Two different possible applications for integrated electro-optic package40 are incorporated into a portable electronic device including dualimage manifestation apparatus 100, a simplified schematic view of whichis illustrated in FIG. 5. Dual image manifestation apparatus 100includes first image manifestation apparatus 112 constructed to providea large virtual image and second image manifestation apparatus 114constructed to provide a direct view image. Apparatus 112 includes areal image generator 115 affixed in overlying relationship to an opticalinput of an optical waveguide 116. An optical output of opticalwaveguide 116 is positioned to be externally available and has a lenssystem, represented by a single lens 117, affixed thereover.

Image generator 115 includes, for example, integrated electro-opticpackage 40 (as illustrated in FIG. 4) mounted on printed circuit board80 and driven by data processing circuits 82, also mounted on printedcircuit board 80. The data processing circuits include, for example,logic and switching circuit arrays for controlling each pixel in the SLMarray of image generator 115. The data processing circuits include, inaddition to or instead of the logic and switching arrays, amicroprocessor or similar circuitry for processing input signals toproduce a desired real image on the diffuser of image generator 115.

In this specific embodiment the pixels are formed in a regular,addressable pattern of rows and columns and, by addressing specificpixels by row and column in a well known manner, the specific pixels areenergized to produce a real image on the diffuser. Digital or analogdata is received at an input terminal and converted by data processingcircuits into signals capable of energizing selected LCDs to generatethe predetermined real image.

As the technology reduces the size of package 115, greater magnificationand smaller lens systems are required. Reducing the size of the lenseswhile increasing the magnification results in greatly limiting the fieldof view, substantially reducing eye relief and reducing the workingdistance of the lens system. Generally, optical waveguide 116 includesone or more optical elements 118 and 119, which may be Fresnel lenses,reflective elements, refractive elements, diffractive elements, etc.Elements 118 and 119 may provide some magnification and/or may reducevarious types of distortion. Lens system 117 is mounted so as to receivethe image from optical waveguide 116, magnify it an additionalpredetermined amount and create an aperture within which a virtual imageis viewed. In the present embodiment, optical waveguide 116 and lenssystem 117 magnify the image a total of approximately twenty times.Generally, a magnification greater than ten (10×) is required to magnifythe real image generated by image generator 115 sufficiently to beperceived by a human eye.

It will of course be understood that lens system 117 may be adjustablefor focus and additional magnification, if desired, or may be fixed in ahousing for simplicity. Because the image received by lens system 117from optical waveguide 116 is much larger than the image at imagegenerator 115, lens system 117 may not be required to provide the entiremagnification and, therefore, is constructed larger and with lessmagnification. Because of this larger size, the lens system has a largerfield of view and a greater working distance, which in turn providesbetter eye relief.

Here it should be understood that the virtual image viewed by theoperator through lens system 117 is relatively large (e.g. 8.5"×11") andappears to the operator to be several feet behind dual imagemanifestation apparatus 100. Because of the size of the virtual imageproduced by image manifestation apparatus 112, a large variety ofalphanumeric and/or graphic images can be easily and convenientlyviewed. Further, image manifestation apparatus 112 is very small andcompact so that it can easily be incorporated into portable electronicdevices, such as pagers, two-way radios, cellular telephones, databanks, etc., without substantially effecting the size or powerrequirements.

Second image manifestation apparatus 114 constructed to provide a directview image includes an image generator 120, which includes integratedelectro-optic package 40 and driver board 80 (as illustrated in FIG. 3)similar to image generator 115, an optical waveguide 122 an opticalelement 124 and a direct view screen 125. Image generator 120 is mountedin overlying relationship on an optical input to optical waveguide 122.The image from image generator 120 is reflected and/or otherwisedirected by an optical element 121 onto optical element 124. Whileelement 124 is illustrated as a separate element, it will be understoodthat it could be incorporated as a portion of optical waveguide 122.Optical element 124 can also include a Fresnel lens, or the like, forfocusing and/or magnification if desired. The image from optical element124 is directed onto screen 125 where it can be directly viewed by theoperator.

Image manifestation apparatus 114 provides a direct view image which canbe no larger than screen 125 upon which it is projected. Because of themuch smaller size of the direct view image, the amount of magnificationrequired is much smaller, i.e. less than approximately 10×. Generally,while the direct view image is much smaller than the virtual imageproduced by image manifestation apparatus 112, more light (larger lightsource) is required to generate the direct view image because more lightis required to project the image onto screen 125. However, because thedirect view image is smaller, any message contained in the direct viewimage must be larger in order to be perceived by the operator. Thus,whereas one pixel in the array of image generator 115 produces one pixelin the final virtual image (for example), several pixels in the array ofimage generator 120 operate in conjunction to produce one pixel in thedirect view image on screen 125. Because several pixels produce onepixel, in many instances the higher light requirement may beautomatically resolved. If additional light is required in someapplications, additional LEDs (described above) or higher current andcorrespondingly higher light output may be utilized as the light source,as one example.

Referring specifically to FIG. 6, a perspective view of dual imagemanifestation apparatus 100 in a portable electronic device isillustrated in a typical housing 145. Screen 125 is visible through anopening in the front of housing 145 for the direct viewing of imagesthereon. Also, an aperture is provided in the front of housing 145 toreceive lens system 117 so that the virtual image produced by imagemanifestation apparatus 112 may be readily viewed. A touch pad 146 isoptionally provided on the front surface of housing 145 for controllinga cursor in the virtual image, which cursor may further controldisplayed keyboards and/or other controls. Additional controls 148 areprovided on an upper surface of housing 145 and generally include suchfeatures as an on/off switch, and controls for any electronic devicesconnected thereto.

Video from a receiver or other data source within the portableelectronic device is communicated to either or both image manifestationapparatus 112 and 114 for convenient viewing by the operator. Generally,for example, control signals titles, etc. may appear in the direct viewimage on screen 125 while larger alpha-numeric messages and graphicswill appear in the virtual image at lens system 117. Also, in someapplications, it is envisioned that dual image manifestation apparatus100 may be constructed so that image manifestation apparatus 112 can bephysically separated from image manifestation apparatus 114, along line147 for example, and each can be used separately. In such an embodimentimage manifestation apparatus 112 is a very low power device while imagemanifestation apparatus 114 generally requires more power and will, forexample, generally contain the portable electronic equipment (e.g. acommunication receiver).

FIGS. 7, 8 and 9 illustrate a front view, side elevational view, and topplan, respectively, of another miniature virtual image display 150 inaccordance with the present invention. FIGS. 7, 8 and 9 illustrateminiature virtual image display approximately the actual size to providesome indication as to the extent of the reduction in size achieved bythe present invention. Display 150 includes an integrated electro-opticpackage 155 which includes, in this specific embodiment, 144 pixels by240 pixels. Each pixel is fabricated approximately 20 microns on a sidewith a center-to-center spacing between adjacent diodes of no more than20 microns. In a preferred embodiment, integrated electro-optic package155 produces a luminance less than approximately 15 fL. This very lowluminance is possible because display 150 produces a virtual image.Further, because a very low luminance is required, LEDs and the like maybe utilized as the light source for the SLM stack, which greatly reducesthe size and power requirements. Integrated electro-optic package 155 ismounted on the surface of a driver board 158. An optical system 165 isalso mounted on driver board 158 and magnifies the image approximately20× to produce a virtual image approximately the size of an 8.5"×11"sheet of paper.

Here it should be noted that because of the very small integratedelectro-optic package 155 and the fact that a virtual image is utilized,rather than a direct view display, the overall physical dimensions ofminiature virtual image display 150 are approximately 1.5 inches (3.8cm) wide by 0.75 inches (1.8 cm) high by 1.75 inches (4.6 cm) deep, or atotal volume of approximately 2 cubic inches (32 cm³).

Referring specifically to FIG. 10, a 4× magnified view in side elevationof miniature virtual image display 150 of FIG. 8 is illustrated forclarity. From this view it can be seen that a first optical lens 167 isaffixed directly to the upper surface of diffuser 57 (see FIG. 3). Anoptical prism 170 is mounted to reflect the image from a surface 171 andfrom there through a refractive surface 172. The image is then directedto an optical lens 175 having a refractive inlet surface 176 and arefractive outlet surface 177. From lens 175 the image is directed to anoptical lens 180 having an inlet refractive surface 181 and an outletrefractive surface 182. Also, in this embodiment at least onediffractive optical element is provided on one of the surfaces, e.g.surface 171 and/or surface 176, to correct for aberration and the like.The operator looks into surface 182 of lens 180 and sees a large, easilydiscernible virtual image which appears to be behind display 150.

It should be noted that in the prior art, pagers and other smallreceivers in which visual displays are desired are especiallyhandicapped by the size of the displays. Generally such displays arelimited to a single short line of text or several digits, and the sizeof the display still dictates the size of the receiver. Utilizing anembodiment of the present invention, a display with several lines oftext to a full page can be incorporated and the size of the receiver orother portable electronic equipment can be substantially reduced.Further, the display is clearer and easier to read and, because itutilizes a virtual display, requires very little power for the operationthereof. In fact, the present display uses much less power than any ofthe direct view displays normally utilized in electronic equipment and,as a result, can be fabricated in much smaller sizes.

Thus a greatly improved portable electronic device with miniaturevirtual image display is disclosed, which incorporates an extremelysmall spatial light modulator array on a semiconductor chip. Because avirtual image display is utilized, the display is constructed very smalland requires very little power. Further, because of the extremely smallsize and power consumption of the virtual image display, it isincorporated into portable electronic equipment without substantiallyeffecting the size or power requirements. The miniature virtual displayprovides a predetermined amount of magnification along with sufficienteye relief and lens working distance to create a comfortable andviewable virtual image. Also, a complete virtual image is produced withno moving parts or power consuming motors and the like. Further, theelectronics provided as a portion of the miniature virtual image displayallows a variety of very small real images to be generated. The verysmall real image is magnified into a large virtual image that is easilyperceived by the operator.

While we have shown and described specific embodiments of the presentinvention, further modifications and improvements will occur to thoseskilled in the art. We desire it to be understood, therefore, that thisinvention is not limited to the particular forms shown and we intend inthe appended claims to cover all modifications that do not depart fromthe spirit and scope of this invention.

What is claimed is:
 1. An integrated electro-optic package forreflective spatial light modulators comprising:an array of reflectivespatial light modulator pixels formed on a substrate with each pixelincluding a control circuit formed in the substrate, each controlcircuit including control terminals adjacent an outer edge of thesubstrate, a mirror positioned on the substrate in overlyingrelationship to the control circuit, and spatial light modulatormaterial positioned in overlying relationship to the mirror so thatlight passing through the spatial light modulator material is reflectedback through the spatial light modulator material; a light polarizinglayer positioned in overlying relationship to the array of reflectivespatial light modulator pixels; a housing with an internal cavity formedto receive the array of reflective spatial light modulator pixels andthe light polarizing layer therein, the housing defining an openinggenerally parallel with and spaced from the light polarizing layer andincluding an optical layer positioned in the opening; an at leastpartially reflective member affixed to the optical layer; a light sourcemounted in the housing so that light emanating from the light source isdirected onto the reflective member and is reflected substantiallyuniformly onto the light polarizing layer; and the optical layerincluding a diffuser forming an image plane for reflected light from thearray of reflective spatial light modulator pixels.
 2. An integratedelectro-optic package for reflective spatial light modulators as claimedin claim 1 wherein the at least partially reflective member includes atleast one diffractive optical element.
 3. An integrated electro-opticpackage for reflective spatial light modulators as claimed in claim 2wherein the housing has a temperature coefficient of expansion that issubstantially similar to the array of reflective spatial light modulatorpixels' temperature coefficient of expansion.
 4. An integratedelectro-optic package for reflective spatial light modulators as claimedin claim 1 wherein the housing is molded plastic.
 5. An integratedelectro-optic package for reflective spatial light modulators as claimedin claim 1 wherein the light source includes a plurality of lightemitting diodes.
 6. An integrated electro-optic package for reflectivespatial light modulators as claimed in claim 5 wherein the plurality oflight emitting diodes includes at least two diodes, each of which emit adifferent color of light.
 7. An integrated electro-optic package forreflective spatial light modulators as claimed in claim 1 wherein thehousing includes a molded plastic and the light source is a plurality oflight emitting diodes embedded in the molded plastic.
 8. An integratedelectro-optic package for reflective spatial light modulators as claimedin claim 1 where, in the array of reflective spatial light modulatorpixels, the layer of spatial light modulator material is a continuouslayer across the entire array and each control circuit for each pixelformed in the substrate includes one contact, the array furtherincluding an optically clear contact positioned on an opposite side ofthe continuous layer with the one contact and the optically clearcontact defining a pixel within the continuous layer.
 9. An integratedelectro-optic package for reflective spatial light modulators as claimedin claim 8 wherein the spatial light modulator material includes liquidcrystal material.
 10. An integrated electro-optic package for reflectivespatial light modulators as claimed in claim 8 wherein the opticallyclear contact for each pixel is formed in a layer of indium-tin-oxidedeposited in overlying relationship to the continuous layer of spatiallight modulator material.
 11. An integrated electro-optic package forreflective spatial light modulators as claimed in claim 8 wherein themirror positioned on the substrate is a polished pad of metal, one foreach pixel, which pad of metal also forms the one contact included inthe control circuit.
 12. An integrated electro-optic package forreflective spatial light modulators as claimed in claim 12 wherein thepolished pad of metal for each pixel is a polished pad of aluminum. 13.An integrated electro-optic package for reflective spatial lightmodulators as claimed in claim 1 wherein the diffuser in the opticallayer is removably mounted and further mounted for axial movement towardand away from the array of reflective partial light modulator pixels toprovide focusing of images formed on the diffuser.
 14. An integratedelectro-optic package for reflective spatial light modulators as claimedin claim 1 wherein the housing include leads formed therein so as to bein electrical contact with the control terminals adjacent an outer edgeof the substrate of each control circuit and the leads further extend toan external portion of the housing to form external contacts for thecontrol circuits.
 15. An integrated electro-optic package for reflectivespatial light modulators as claimed in claim 14 wherein the housing ismolded and the leads are a leadframe molded into the housing.
 16. Anintegrated electro-optic package for reflective liquid crystal spatiallight modulators comprising:a reflective liquid crystal spatial lightmodulator stack including a substrate with a plurality of controlcircuits formed therein, each control circuit including controlterminals adjacent an outer edge of the substrate and an electricalcontact mirror positioned on the substrate, each electrical contactmirror defining a pixel and a first electrical contact for the pixel, alayer of liquid crystal spatial light modulator material positioned inoverlying relationship to the electrical contact mirrors so that lightpassing through the liquid crystal spatial light modulator material isreflected back through the liquid crystal spatial light modulatormaterial, and an electrically conductive optically transparent layer ofmaterial positioned on an opposite surface of the liquid crystal spatiallight modulator material to form a second electrical contact for eachpixel; a light polarizing layer positioned in overlying relationship tothe electrically conductive optically transparent layer of material; ahousing with an internal cavity formed to receive the light polarizinglayer and the stack therein, the housing defining an opening generallyparallel with and spaced from the light polarizing layer and includingan optical layer positioned in the opening; an at least partiallyreflective member affixed to the optical layer; a light source mountedin the housing so that light emanating from the light source is directedonto the reflective member and is reflected substantially uniformly ontothe light polarizing layer; and the optical layer including a diffuserforming an image plane for reflected light from the array of reflectivespatial light modulator pixels.
 17. An integrated electro-optic packagefor reflective liquid crystal spatial light modulators as claimed inclaim 16 wherein the layer of liquid crystal spatial light modulatormaterial is contained within a closed cavity having internal opposedflat surfaces, the electrical contact mirrors are affixed to one of theinternal surfaces and the electrically conductive optically transparentlayer is affixed to the other of the internal surfaces.
 18. Anintegrated electro-optic package for reflective liquid crystal spatiallight modulators as claimed in claim 17 wherein the closed cavity isdefined by a surface of the substrate, a tubular spacer affixed to thesurface of the substrate and a glass plate affixed over the tubularspacer.
 19. An integrated electro-optic package for reflective liquidcrystal spatial light modulators comprising:a reflective liquid crystalspatial light modulator stack includinga substrate with a plurality ofcontrol circuits formed therein, each control circuit including controlterminals adjacent an outer edge of the substrate and an electricalcontact minor positioned on the substrate, each electrical contact minordefining a pixel and a first electrical contact for the pixel, a layerof liquid crystal spatial light modulator material positioned inoverlying relationship to the electrical contact minors so that lightpassing through the liquid crystal spatial light modulator material isreflected back through the liquid crystal spatial light modulatormaterial, and an electrically conductive optically transparent layer ofmaterial positioned on an opposite surface of the liquid crystal spatiallight modulator material to form a second electrical contact for eachpixel; a housing with an internal cavity formed to receive the stacktherein and the stack being positioned in the internal cavity; a lightpolarizing layer positioned in the internal cavity of the housing inoverlying relationship to the electrically conductive opticallytransparent layer of material, the housing defining an opening in theinternal cavity generally parallel with and spaced from the lightpolarizing layer and including an optical layer positioned in theopening so as to receive polarized reflected light from the electricalcontact minors on the substrate of the stack; an at least partiallyreflective member affixed to the optical layer of the housing; a lightsource mounted in the housing so that light emanating from the lightsource is directed onto the reflective member and is reflectedsubstantially uniformly through the light polarizing layer and onto thestack; and the optical layer of the housing including a diffuser formingan image plane for reflected light from the stack.
 20. An integratedelectro-optic package for reflective liquid crystal spatial lightmodulators as claimed in claim 19 where, in the reflective liquidcrystal spatial light modulator stack, the layer of liquid crystalspatial light modulator material is contained within a closed cavityhaving internal opposed flat surfaces and defined by a surface of thesubstrate, a spacer affixed to the surface of the substrate and a glassplate affixed over the spacer with the electrical contact mirrorsaffixed to one of the internal surfaces and the electrically conductiveoptically transparent layer affixed to the other of the internalsurfaces.
 21. A method of fabricating an integrated electro-opticpackage for reflective spatial light modulators comprising the stepsof:providing a stack including a plurality of reflective spatial lightmodulators formed in a two dimensional array on a semiconductorsubstrate with drive electronics formed in the substrate for eachspatial light modulator of the array of spatial light modulators andcontrol terminals for the drive electronics positioned adjacent outeredges of the substrate, the stack further including a light transparentsurface defining a light input and light output for each of the spatiallight modulators in the two dimensional array of reflective spatiallight modulators; forming a housing with an internal cavity constructedto receive the stack therein and positioning the stack in the cavity;forming a light polarizing layer and positioning the light polarizinglayer in the internal cavity of the housing in overlying relationship tothe stack, the housing defining an opening in the internal cavitygenerally parallel with and spaced from the light polarizing layer;forming an optical layer and positioning the optical layer in theopening of the housing so as to receive polarized light from the stack;forming an at least partially reflective member and affixing thepartially reflective member to the optical layer of the housing;providing a light source and mounting the light source in the housing sothat light emanating from the light source is directed onto thereflective member and is reflected substantially uniformly through thelight polarizing layer and onto the stack; and diffusing light reflectedfrom the stack to form an image.
 22. A method of fabricating anintegrated electro-optic package for reflective spatial light modulatorsas claimed in claim 21 wherein the step of diffusing light reflectedfrom the stack includes a step of forming the optical layer of thehousing so as to include a diffuser constructed to form an image planefor reflected light from the stack.
 23. A method of fabricating anintegrated electro-optic package for reflective spatial light modulatorsas claimed in claim 21 wherein the step of forming a housing furtherincludes the step of forming the housing to include a plurality ofelectrical leads each positioned therein so as to provide a firstcontact in the cavity and a second, electrically coupled contact at anexternal surface of the housing.
 24. A method of fabricating anintegrated electro-optic package for reflective spatial light modulatorsas claimed in claim 23 wherein the step of forming a housing includesmolding the housing from plastic.
 25. A method of fabricating anintegrated electro-optic package for reflective spatial light modulatorsas claimed in claim 24 wherein the step of molding the housing fromplastic includes a step of molding a leadframe into the plastic to formthe plurality of electrical leads.
 26. A method of fabricating anintegrated electro-optic package for reflective spatial light modulatorsas claimed in claim 24 wherein the step of molding the housing fromplastic and the step of mounting the light source in the housing includeforming the housing with at least one alcove in communication with thecavity and adjacent the stack, and positioning at least one lightemitting diode in the alcove.